Alkoxy diaminostilbenedisulfonic acids



United States Patent Ofiice 2,848,484 Patented Aug. 19, 1958 group consisting of chloro and alkoxy,

--the art.

ALKOXY DIAMINOSTILBENEDISULFONIC ACIDS This invention relates to new'optical bleaching agents and more specifically to new optical bleaching agents of the formula:

SlOaM SOaM in which X is an alkoxy group, Y is selected from the R is an aryl radical and M is hydrogen, an alkali metal cation or am- NHCOR monium. The new compounds of this invention are useful as brighteners for cotton.

The use of optical bleaching agents-to compensate for the natural yellowing of fibers has become common in These compounds absorb ultra-violet light and reemit light in the blue range, thus, automatically compensating for the yellow of the fiber. Since more visible light is reflected than is incident upon the fiber, the cloth actually appears to be whiter than ordinary white bleached cloth.v Such compounds must have afiinity for the fiber and their fluorescence must be in the blue range. The additive efiect of yellow reflected light and blue fluorescence which results in an overall increase in total reflected light sharply differentiates this type of bleaching from the subtractive effect obtained-When one uses the older type of bluing which dyed the'cloth a blue to compensate for the yellow.

It is essential in these compounds that the fluorescence be as much as possible a true blue. However, many brighteners are quite usable which fiuoresce either reddish or greenish shades of blue.- Many brighteners have been described in the prior art as being derived from diaminostilbene disulfonic acid. Most of these fiuoresce a reddish shade of blue. Brighteners derived from chlorinated diaminostilbene disulfonic acids have been described. Even these have a distinctly reddish shade of blue fluorescence. The compounds which form our invention possess a greenish shade of blue fluorescence which had been obtainable heretofore only Withother, more expensive, intermediates. It is most surprising that the replacement of even one chlorine in a dichloro-diaminostilbene disulfonic acid with an alkoxy group will give an intermediate from which greenish shade brighteners can be obtained.

One would not expect this change to have such a marked effect on the shade of fluorescence as to shift it from reddish blue to a greenish blue.

The compounds of our invention are useful in brightening cotton. They can be used by themselves or they can be used in blends with redder shade brighteners to produce a neutral blue fluorescent effect on the cloth.

The compounds of our invention may be prepared in a number of ways; The appropriate 5-.alkoxy-4-nitrotoluene-2-sulfonic acid may be oxidized directly with sodium hypochlorite to form the 5,5-dialkoxy- 4,4-dinitrostilbene-2,2'-disulfonic acid which can then be reduced and acylated. The toluene derivative from which this process starts is prepared from the corresponding chloro compound by reaction with a sodium alkoxide, such as sodium methoxide, sodium ethoxide, or the like.

The reduction of the nitrostilbene is carried out by known methods and the corresponding diamino-dialkoxystilbenedisulfonic acids which are formed are themselves new compounds which form a further aspect of our invention.

The-compounds of our invention can also be prepared by forming the dichloro-dinitrostilbene-disulfonic acids by known methods and treating the same with a sodium alkoxide. We have found that in such a preparation a most surprising phenomenon is observed. Even with a large excess of sodium alkoxide, only oneof the chlorine atoms is replaceable by alkoXy under the conditions used and thus, the compounds of our invention which are unsymmetrical are best prepared in this manner.

The acylation of the intermediatediaminostilbene derivatives is carried out by known methods using a variety of acylating agents. Among the 'acylating agents which may be used there can be cited-benzoyl chloride and its derivatives such as 2,4-dimethoxybenzoyl chloride, 2,4- diethoxybenzoyl chloride, o-methoxybenzoyl chloride, 0- ethoxybenzoyl chloride, 2,5-dimethoxybenzoyl chloride, 2,5-diethoxybenzoyl chloride, p-methyl-o-methoxybenzoyl chloride, p-methoxybenzoyl chloride, p-benzoylaminobenzoyl chloride and the like; other aromatic acid chlorides such as the naphthoyl chlorides, diphenyl-4-carboxy chloride, and the like; triazine chlorides such as cyanuric chloride; and heterocyclic acid chlorides such as nicotinoyl chloride, picolinoyl chloride, thenoyl chloride and similar acid chlorides. Since the triazine residue. is used in the brightener art to replace acyl groups in brightener structures, the term acyl must be interpreted to include this type of radical. When a chloro triazine such as cyanuric chloride is used, it can be condensed with either one or two mols of the alkoxy substituted diaminostilbene disulfonic acids or the diaminostilbene derivative can be condensed with two cyanuric chlorides. In such case, the other chlorines in the triazine nucleons can be replaced with a variety of groups such as hydroxyl, alkoxy, phenoxy, anilino, morpholino, bis-,8 hydroxy ethylamino, mono-B-hydroxy ethylamino and the like in any combination desired. Any amino groups on stilbene moieties which have not been acylated can be further acylated with benzoyl chloride derivatives, orother agents such asthose mentioned above. In order to obtain the best brightening efiect, all the free amino groups should be acylated in one way or another.

The brightenersof our invention are sulfonic acids or their salts. In order to get application tothe cloth the salts must be soluble in water. It is therefore preferable to use the alkali metal or ammonium salts, although in some case is the brighteners of our invention may be dyed on cotton using a bath containing soap solutions, or they may be applied by any of the usual laundry techniques. They are primarily brighteners for cotton but have substantivity on viscose rayon. Under the proper conditions, that is, slightly acid baths, the compounds of our invention will also show substantivity to nylon and to animal fibers, such as wool and silk.

It is an advantage of the brighteners of our invention that they have very similar substantivity on cotton to that of the other diaminostilbene type brighteners. They are therefore very compatible with'such brighteners in the formation of blends of a neutral blue fluorescence,

Our invention can be illustrated by the following examples in which the parts are by weight unless otherwise specified.

Example 1 SOsH H OsS A mixture of 4 parts of disodium 5,5'-dichloro-4,4 The product, 5,5'-dimethoxy-4,4'-dinitrostilbene-2,2-didinitrostilbene-2,2-disulfonate, 119 parts of methanol sulfonic acid, is separated by filtration and dried. and 2.65 parts of sodium methylate is refluxed for 20 hours. A small amount of alcohol-insoluble material is separated by filtration from the hot solution. The alcohol solution is then evaporated and cooled. The product, which is the disodium salt of 5-methoxy-5-chloro- O 4,4'-dinitrostilbene-2,2-disulfonic acid, is isolated by fil- 5 tration and dried.

The product of Example 3 is reduced to the corre- Example 4 Example 2 sponding diamino compound by using the procedure of S0511 Hols Example 2. The product formed is the 5,5'-dimethoxy- 4,4'-diaminostilbene-2,2'-disulfonic acid. HzN CELT-CH NH2 Example 5 CH3 C1 SOsH 11055 A mixture of 10 parts of Master Builders Iron Grade HzN CH=CH NH, D, 100 parts of water and 0.5 part by volume of glacial acetic acid is heated to reflux. A solution of 2.5 parts 011150 01H; of 5-methoxy-5'-chloro-4,4-dinitrostilbene-2,2-disulfonic Th procedure f Example 3 i f ll w d using 31 acid disodium salt in 35 parts of water is added to the parts of sodium ethylate instead f 5 7 Parts f sodium mixture. The IflUXi11g is continued until ICdllCtiOIl is methylate The corresponding 5-3thoxy prcduct is obcomplete. The reaction mixture is then made alkaline mi d Thi product i th idi b Sodium b y h addition 2 Parts Of S01id S0diu111 cafhonaiepochlorite solution, following the procedure of Example The iron sludge is separated by filtration and the filtrate 3, t give th corresponding 5,5'-diethoxydinitrostilbene a idifi d wi hf hydrochloric add t0 give a disulfonic acid. The latter is then reduced using the strongly positive test on Congo Red indicator paper. procedure of Example 2, to give the 5,5-diethoxy-4,4'- The Solution is reduced y boiling to one-half of its voldiaminostilbene-2,2-disulfonic acid. By the use of ume and then cooled in an ice bath. The product, 5- sodium butoxide in place of the sodium ethylate, the cormethoxy-5-chloro-4,4 diaminostilbene 2,2 disulfomc responding butoxy compounds are prepared by these proacid, is isolated by filtration and dried. cedures.

Example 6 SOsNa Naoas omoQomvHOoikoHQNncoQocm CH: (SCH: 1 CH;

Example 3 40 To 60 parts of pyridine is added, 2.64 parts of re- H083 distilled thionyl chloride and then 3.64 parts of 2,4-dimethoxybenzoic acid. To this mixture is added 2.7 parts om CH=CH N of the product of Example 2. The reaction mixture is heated at reflux until a sample gives a negative test for OHro bCHr free amine when diazotized and spotted versus R-salt A mixture of 27.4 parts of 94.9% sodium 5-ch1oro-4- sohmonv nitrotoluene-Z-sulfonate, 143 parts of methanol and 5.7 After addltlon of 6 B 3 F carbollate parts of sodium methylate is heated at reflux until the 5- Parts of Water, the py 1S dlstlued Off Wlth Steamchloro group has been entirely replaced by a methoxy To the Tfimainhlg Solution, 15 Parts Of Sfl1ti dd d and group. The hot solution is then clarified by filtration :0 t reaction rmxture cooled- The p and evaporated to dryness. bis (2,4 dimethoxybenzamido) 5 methoxy 5' A i t f 149 parts f th di 5-metb0 y-4- chlorostilbene-2,2-disulfonate, is isolated by filtration nin'otoluene-2-sulfonate, obtained above, 26 parts by voland dried. The product obtained is soluble in water and ume of 30% sodium hydroxide solution and 260 parts of imparts to cotton a strong greenish blue fluorescence.

Example 7 SO=Na Naors CzHs CHs $011: $C1Hs water is warmed to C. To this mixture is added 31 The procedure of Example 6 is followed using an parts by volume of sodium hypochlorite solution of equivalent quantity of o-ethoxybenzoic acid in place of specific gravity 1.210 having 12.3% available chlorine. the 2,4-dimethoxybenzoic acid, and the product of Ex- The mixture is stirred at 60 C. until reaction is com- 69 ample 4 in place of the product of Example 2. The

plete. To isolate the product, 70 parts of sodium chloproduct formed imparts to cotton 8. strong greenish blue ride is added and the reaction mixture cooled externally. fluorescence.

Example 8 SOiNa NaO;S

ONE N NE orl=orr NH N NEG r; 9 Q. l;

21.4 parts of the product of Example 5 is dissolved in 240 parts of water, 160 parts of acetone is then added and the solution is cooled to C. A second solution of 18.4 parts of cyanuric chloride in 80 parts of acetone is added gradually for the first solution, simultaneously with sufficient sodium carbonate solution to keep the solution approximately neutral during the addition. The mixture is stirred until a reaction is approximately complete. 93 parts of aniline is then added slowly to the mixture accompanied by the addition of further portions of sodium carbonate to keep the mixture neutral. The mixture is stirred at 55 C. until this condensation is complete, when 15.3 parts of monoethanolamine is added. The acetone is removed by distillation and replaced with an equal volume of water. The mixture is then stirred at the boil to produce a compound having the above formula. Three hundred parts of Water is added and the mixture is further treated after reheating with 71.5 parts of 10% carbonate solution. On cooling the product is isolated by filtration as the sodium salt and washed with 10% brine. The yield is excellent. The free sulfonic acid may be prepared from the sodium salt illustrated above by the addition of an equivalent amount of a strong mineral acid. The acid can of course be converted into its ammonium or alkali metalsalt by conventional neutralization with the corresponding base.

Example 9 A stock solution of brightener is made by dissolving 100 mg. of brightener in liters of distilled water. Also, a stock soap solution is prepared by dissolving g. of soap powder in 2 liters of distilled water.

Three one-pint laundry jars are used for the test. To the first is added 7.2 cc. of stock brightener solution; to the second is added 8.1 cc. and to the last 9.0 cc. of stock brightener is added. Then to each jar, 100 cc. of stock soap solution is added. Then distilled water is added until the total volume is 150 cc. To each jar is added a 5 g. piece of 80 x 80 cotton. The jars are then closed and placed in a Laundrometer at 130 F. for 25 minutes. At the end of this time the jars are opened and the fabrics rinsed three times in cold water and then dried. The dyed fabric from each jar is then viewed under ultra-violet light. It is found to appear quite white when compared with untreated cloth.

Example 10 Using the dye test of Example 9, the brightener derived from the intermediate of Example 4 by the procedure of Example 6 is found to fluoresce a greener shade of blue than a stilbene brightener of similar structure lacking the 5 and 5-methoxy groups.

Example 11 When the intermediate of Example 2 is converted to a brightener by the method of Example 6 and dye tested by the method of Example 9, the cotton cloth fluoresces a greener shade of blue than cloth similarly dye tested using the brightener of the same structure except'for presence of chlorines instead of methoxyl groups in the 5 and 5' positions.

Example 12 If the intermediate of Example 4 is aroylated with oethoxybenzoyl chloride using the method of Example 6 and the resultant brightener dye tested by the method of Example 9, a greener shade fluorescence under U. V. light is observed than is observed from a similar brightener which lacks the methoxy groups in the 5 and 5 positions.

We claim: 1. A compound of the formula:

801M MOaS Z-HN OH=CH NH-Z References Cited in the file of this patent UNITED STATES PATENTS 2,681,926 Lane et al. June 22, 1954 2,687,431 Marschall Aug. 24, 1954 2,688,617 Hein et al. Sept. 7, 1954 2,690,453 Savidge et al. Sept. 28, 1954 

1. A COMPOUND OF THE FORMULA: 